1. Field of the Invention
The present invention relates to a novel phosphite antioxidant for polymeric resin compositions, and more particularly relates to stabilized resin compositions and stabilizer concentrates for resin compositions.
2. Description of Related Art
Phosphite stabilizer compositions comprising 2,2,6,6-tetramethylpiperidin-4-ol, reportedly a Hindered Amine Light Stabilizer (HALS) building block, are known in the art.
U.S. Pat. No. 3,467,733 discloses cyclic phosphites and diphosphites, such as bis(1,3,2-di-oxaphosphorinanyl-2-oxy)aryl alkanes and mono- and bis(1,3,2-di-oxaphosphorinanyl-2-oxy)benzenes, that are said to be useful as stabilizers for organic compositions, such as rubber and polyvinyl chloride, and are made by reacting a cyclic phosphorohalidite with a hydroxy aromatic compound, subsequently neutralizing the reaction product with a nitrogen-containing compound, such as ammonia, and recovering the desired phosphite or diphosphite.
U.S. Pat. No. 3,714,302 discloses cyclic phosphites that are produced by reacting phenol in the melt with a crude reaction product or PCl3 and a 2,2-di-lower alkyl-1,3-propane glycol and recovering the desired product by distillation. The cyclic phosphites are said to be useful as stabilizers for organic compositions, such as rubber and polyvinyl chloride.
U.S. Pat. No. 4,096,114 discloses organic phosphites having at least one 2,2,6,6-tetramethyl piperidyl substituent attached at the 4-position to phosphorus through oxygen, and at least one polyol or polyphenol group, which are said to be superior light and heat stabilizers for organic polymeric materials, such as polyethylene, polypropylene, polyvinyl chloride, acrylonitrile-butadiene-styrene terpolymers, polyamides, polystyrene, and similar polymers.
U.S. Pat. Nos. 5,424,348 and 5,623,009 disclose a phosphite having the formula:
wherein Y1 is an alkyl group and Y2 is selected from the group consisting of sec-butyl and tert-butyl. The phosphite is said to exhibit enhanced stability including hydrolytic and UV stability, and to be useful in stabilizing thermoplastic compositions.
U.S. Pat. No. 5,594,053 discloses a stabilized thermoplastic composition comprising a stabilizing amount of a phosphite of the formula:
R1 is independently selected from the group consisting of alkyl groups having from 1 to 9 carbon atoms, Y is independently selected from the group consisting of hydrogen, halogen, or alkyl; and the —O—X groups are positioned at the respective ortho- or para- positions with respect to the diphenyl linkage, the remaining ortho- and para- positions with respect to the —O—X linkage being occupied by R1 whereby the —O—X groups are hindered by the presence of at least one R1 group; R2 group is a divalent alkylidene radical having from 1 to 6 carbon atoms or a direct bond; and wherein X has the formula:
z1 and z2 can be 0 or 1; and R3, R4 and R5 are independently selected from the group consisting of hydrogen, halogen, or alkyl.
U.S. Pat. No. 5,607,989 discloses a piperidinyl phosphite composition consisting of a piperidinyl phosphite compound and an additive having a melting point of greater than 155° C. selected from the group consisting of (i) sorbitol compounds, (ii) phosphite compounds and (iii) sterically hindered phenolic compounds, and polyolefin compositions containing them.
U.S. Pat. No. 5,616,636 discloses a composition comprising: a) a compound containing a phosphite or phosphonite group and at least one 2,2,6,6-tetraalkylpiperidinyl group, and b) a polyolefin which has been produced in the presence of a catalyst which is either i) a supported Ziegler catalyst or ii) a metallocene catalyst, from which polyolefin the catalyst has not been removed.
U.S. Pat. No. 5,618,866 discloses a phosphite and stabilized thermoplastic composition comprising the phosphite where the phosphite has the formula:
In the above compound, R7 and R8 are preferably alkyl of from 1 to 6 carbon atoms, R9 is preferably alkyl of 1 to 12 carbon atoms, m is from 0 to 5. The dicumyl group includes the OX groups which are the phosphite portion. The OX group is hindered by only one alkylaryl group at the ortho position with the other ortho position being occupied by hydrogen. X has the following formula:
wherein R2 is independently selected from the group consisting of alkyl groups having from I to 12 carbon atoms, z1 and z2 can be 0 or 1, and R3, R4 and R5 are independently selected from the group consisting of hydrogen, halogen, or alkyl of from 1 to 3 carbon atoms.
U.S. Pat. No. 5,654,430 discloses oligomeric compounds of the formula I
in which R is a group of the formula
where the oxygen in the group R is in each case bonded to the phosphorus in the recurring structural units and the radical R2 or the carbon in the 4-position of the piperidinyl ring in the group R is in each case bonded to the oxygen in the recurring structural units; and
R1 is C1-C25 alkyl, C2-C25 alkyl which is interrupted by oxygen, sulfur or >N—R3; C2-C24 alkenyl, unsubstituted or C1-C4 alkyl-substituted C5-C15 cycloalkyl; unsubstituted or C1-C4 alkyl-substituted C5-C15 cycloalkenyl; C7-C9 phenyl alkyl which is unsubstituted or substituted on the phenyl ring by C1-C4 alkyl; or tetrahydroabietyl,
R2 is C1-C18 alkylene, C2-C28 alkylene which is interrupted by oxygen, sulfur or >N—R3; C4-C8 alkenylene or phenylethylene,
R3 is hydrogen or C1-C8 alkyl,
m is 0 or 1, and
n is a number from 2 to 25,
where the group R, the radicals R1, R2 and R3 and the index m are identical or different in the recurring structural units of the formula. The compounds are said to be useful as stabilizers for organic materials against oxidative, thermal or light-induced degradation.
East German 290906 discloses olefins stabilized against thermo- and photooxidative degradation with phosphite and phosphonite esters based on hindered amino alcohols and phenols or in the form of 1,3,2-dioxaphosphorus heterocyclic compounds. Thus, isotactic polypropylene containing bis(2,2,6,6-tetramethyl-4-piperidinyl) 2,6-di-tert-butyl-4-methylphenyl phosphite (I) at 180° C. had an autoxidation inductive period greater than 1000 minutes, compared to 47 minutes in the absence of (I) or 410 minutes in the presence of a BHT control.
DEOS 2,905,808 discloses the preparation of a phosphite comprising 2,2,6,6-tetramethylpiperidin-4-ol and pentaerythritol in a three-step reaction.
Chmela, {hacek over (S)}. et al., Polymer Degradation and Stability 39:367-371(1993) disclosed the use of organic phosphites combined with HALS “as stabilizers in the photo- and thermoxidation of polypropylene film. The efficiency of the mixture of HALS and phosphite was compared with the efficiency of the combination of HALS and phosphite in one molecule. A strong synergistic effect was observed for the molecule with HALS and phosphite moieties. Generally, the mixture of HALS and phosphite exhibited synergistic, antagonistic or additive effects. The efficiency of the mixture depends upon the chemical structure of the phosphite and HALS structural units as well as on the ratio of the components.”
Thus, it is seen that organic phosphites are known in the art as secondary antioxidants and costabilizers for polyolefins. Additional examples of such known phosphites are given in H. Zweifel (Ed) Plastics Additives Handbook, 5th edition, Hanser Publishers, Munich 2000. However, there continues to be a demand for an effective phosphite stabilizer for organic materials that are sensitive to oxidative, heat, and/or light-induced degradation. There also continues to be a demand for such a stabilizer to be available in liquid form and for a phosphite stabilizer containing a HALS structural unit.
The disclosures of the foregoing are incorporated herein by reference in their entirety.